1. Field of the Invention
The present invention relates to an optical component and a laser irradiation apparatus, and more particularly to the optical component for fixing a lens used in an optical system for shaping a laser light, and to a laser irradiation apparatus having the optical component.
2. Related Art
In a step for manufacturing a semiconductor device such as a thin film transistor (TFT), a method in which the laser light is irradiated (a laser annealing method) is employed in the step of crystallization, activation, or the like.
When the laser light is irradiated to a substrate to be processed in the step of manufacturing the semiconductor device, a part of the irradiated laser light becomes reflected light or return light.
When the incident laser light interferes with the reflected light from a rear surface of the substrate by overlapping with each other on the semiconductor film, there are problems that the crystallinity of the semiconductor film becomes inhomogeneous for example in the crystallization step and so on. The inhomogeneous crystallinity of the semiconductor film causes variation of the characteristic of TFT.
In addition, when the reflected light is irradiated to an optical component constituting the laser irradiation apparatus, there are problems that the optical component is damaged and so on. When the dust generated by the damage of the optical component is mixed into the semiconductor film as the impurity, the characteristic of the TFT also varies.
Such a variation of the characteristic of TFT may cause a malfunction of a circuit. Therefore, it has been demanded to develop an apparatus in which the laser light can be irradiated while preventing the interference of the laser light, while preventing the optical component from being damaged, or while minimizing such a damage.